1. Field of the Invention
The invention relates to the technical field of planar display and, more particularly, to a brightness control method and device for a display.
2. Description of Related Art
Currently, with the development of electronic technology, portable electronic products such as mobile phones, personal digital assistants (PDA), and MP3 players are getting more and more popular. Such products typically have a small screen with a panel. The panel can be a liquid crystal display (LCD), an organic light-emitting diode (OLED) or other typical planar displays. However, such products are only equipped with cells, which provide limited power. To overcome this drawback, these products typically adjust their displays to an appropriate brightness in order to increase the use time of an entire system.
Typically, the current consumed by a planar display is increased with a higher brightness displayed on the display. For example, a higher brightness indicates a higher current consumed by a backlight for an LCD at the same gray scale. In an OLED display, a higher brightness indicates that a current consumed is increased at a single display pixel.
Existing brightness control methods for a display include: (a) automatically reducing a backlight brightness or closing the backlight after certain use-suspended time is counted to accordingly save power; and (b) calculating brightness distribution statistics of a frame in an operation mode of a display, for example, reducing the backlight brightness when most gray values of the frame are concentrated on the darker image regions (such as most gray values are smaller than 50) in a video playing mode. Conversely, when most gray values of the frame are concentrated on the light image regions, the backlight brightness remains in the normal mode, such that human eyes are insensitive to the poor frame quality produced by the reduced brightness. However, the method (A) directly affects the entire frame's brightness and can save power only at an idle mode. In addition to calculating the brightness distribution statistics, the method (B) needs a frame buffer to store the entire frame, which makes the circuit design become relatively complex and increases the system cost.
Therefore, it is desirable to provide an improved method to mitigate and/or obviate the aforementioned problems.